Unprecedented my ruddy, red, rectum, practically every President that has ever been in office has had conflicts with Congress over testimony in hearings from members of the Executive Branch. They have all gone through the court systems to decide who is right and who is wrong and no Congress has ever considered impeaching any of them before. Obama used the same system to keep his staff members from testifying in Congress on the Fast and Furious case. It's not obstructive, it's the fucking Constitution. Three coequal branches of government, the Legislative Branch, the Executive Branch, and the Judicial Branch. One of the responsibilities of the Judicial Branch is to rule on instances where the Legislative Branch and the Executive Branch have conflicts which each other. If the Executive Branch had to always do what the Legislative Branch demanded then the two branches would not be coequal now would they.